1. Technical Field
The present invention relates to a self-cleaning litter box and more particularly to a self-cleaning litter box, which, in one embodiment, includes a disposable litter cartridge and an automatic rake assembly.
2. Description of the Prior Art
Various litter boxes are known in the art. Both reusable and disposable litter boxes are known. Reusable litter boxes are normally formed from plastic and are configured as a rectangular tray with 3-4 inch sidewalls. Normally, such reusable litter boxes need to be maintained daily or every few days. In order to facilitate the care and cleaning of litter boxes, disposable litter boxes have been developed. Examples of such disposable litter boxes are disclosed in U.S. Pat. Nos. 4,171,680; 4,271,787 and 6,065,429. Such disposable litter boxes normally include a disposable box or tray filled with an absorbent material, commonly known as kitty litter.
In order to further facilitate the upkeep of such litter boxes, self-cleaning litter boxes have been developed. Commercially available self-cleaning litter boxes primarily use “clay” or “clumping” litters and require the periodic addition of fresh kitty litter and the removal of waste every few days. Examples of such self-cleaning litter boxes are disclosed in U.S. Pat. Nos. 4,574,735; 5,048,465; 5,477,812; 6,082,302; 6,378,461; and Re 36,847, hereby incorporated by reference.
U.S. Pat. No. 4,574,735 discloses a self-cleaning litter box which includes a generally circular upper chamber, a lower disposable container, and a rotatable rake assembly. The rotatable rake assembly includes a plurality of tines that are horizontally oriented and connected to a centrally located spindle. The spindle, in turn, is driven by an electric motor by way of a gearing arrangement. Accordingly, when the electric motor is energized, the tines are rotated, thus pushing the solid waste products towards a discharge opening in the upper chamber that is in communication with the lower waste container. Unfortunately, such a configuration is not entirely efficient since it is known that, not all of the waste is discharged into the lower waste container.
In order to solve this problem, self-cleaning litter boxes have been developed which rely on linear motion of a rake assembly to deposit the waste into a waste compartment, located at one end of the litter box. For example, U.S. Pat. No. 5,048,465 discloses a self-cleaning litter box which includes a rake assembly, a removable and reusable lifter tray and a disposable or reusable waste receptacle disposed at one end of the reusable litter tray. The rake assembly includes a plurality of tines used to comb in a linear motion fashion through the litter box. The tines are pivotally mounted. A stop, mounted at one end of the litter tray, causes the tines to rotate and lift the solid waste upwardly and over a wall separating the litter tray and the waste compartment. Once the extended end of the tines are rotated above the wall, continued motion of the rake assembly causes the extended ends of the tines to lift a lid and drop the solid waste products into the waste compartment. Although the self-cleaning litter box system disclosed in the '465 patent facilitates upkeep of the litter box, the litter tray must be refilled often; a cumbersome task. Further, the entire system must be periodically emptied and disassembled for cleaning; also a cumbersome task. Also, the relative complexity of the device results in the cost of the device being relatively expensive.
U.S. Pat. Nos. 5,477,812; 6,082,302; 6,378,461; and Re. 36,847 also disclose self-cleaning litter boxes. Like the '465 patent, the self-cleaning litter boxes disclosed in these patents also include a reusable litter tray and a disposable waste container.
There are various problems associated with the self-cleaning litter boxes disclosed in the above-mentioned U.S. patents. First, because these boxes often require the use of clumping litter, the waste bin fills quickly with clumped urine and solid waste. Therefore the waste bin must be emptied every few days or more frequently, especially in multiple cat applications. Second, removal of the waste container is cumbersome and often requires the user to come in contact with the waste. Third, fresh kitty litter must be added to the litter tray on an on-going basis. Fourth, the drive assembly in such self-cleaning litter boxes is known to include a drive motor that travels with the rake assembly in a toothed track that is exposed to the litter area. By mounting the motor to the rake, electrical power is applied to a movable chassis, thus requiring a take up reel for an electrical cord, which is known to be inherently risky and prone to failure. When too much litter is used in the litter tray, the motor can be insufficient to drive the rake through the litter, thereby causing a jam which requires the owner to intervene. Conversely, if too little litter is used, or if the cat redistributes the litter in a particular way, a clump can cement to the bottom of the litter pan and prevent the rake from passing through the litter area. In other instances, the cat causes litter to accumulate in the tracks, also causing damage to the drive system and/or requiring further user intervention. Further, the electrical motor is not fully protected from urine, and can be damaged by the cat through normal operation. This motor is also known to be loud if the box is placed in close proximity to the user. Fifth, known self-cleaning litter boxes are not suitable for use with crystal litter. In particular, due to the irregular shape of the crystal litter and tendency to pack and interlock, a wave tends to build up in front of the rake assembly, which among other things, may prevent the rake assembly from completing a cleaning stroke. Thus, there is a need for a self-cleaning litter box which is) easier to use than known self-cleaning litter boxes; is more reliable; does not expose electrical or mechanical components to contamination; eliminates the need for a take up reel; and is suitable for use with non-dumping litters such as crystal litter.